The present invention is a safety cabinet having a self-closing and sequencing door mechanism. It is very important for safety cabinets storing flammable, volatile or explosive materials to have doors which automatically close in a tight fit and are flush with the edges of the safety cabinet. A tight and flush fit is necessary to completely seal off the inside of the safety cabinet from the outside thereby protecting the contents from an external hazard or conversely protecting the outside surrounding area from an internal hazard. Safety storage cabinets are desirably constructed such that the doors automatically close after opening in order to assure that the flammable, volatile or explosive material remaining within the cabinet are not exposed. Safety cabinets so constructed reduce the risk of danger in storing hazardous materials.
A majority of door sequencing devices in the art operate on the principle of having a blocking means for holding one door open while allowing a second door to completely close thereby triggering a mechanism to remove the blocking means from the first door. The mechanics of this operating principle usually involves a series of parts to translate vertical motion of the closing door into horizontal motion for removing a blocking means from a different door. Most of the devices in the art use a lever or series of levers and a bellcrank to effectuate the closing of doors in a specified sequence. With exception to the conventional lever door sequencing means are, among others, U.S. Pat. No. 4,265,051 (1981) which uses a pivotable prop located in a contacting arrangement with both doors at the edge opposite the door hinge of each door in order to coordinate the closing movement of the doors. Another device which operates with exception to the lever system is that described in U.S. Pat. No. 4,967,512 (1990), requiring the movement of guide rollers along a cross beam or track on the fixed frame of the cabinet to control the closing sequence of the doors.
Most devices however, including the present invention, operate on the principle of blocking the closure of one door while allowing the other door, usually a door with a sealing flange or lip, to securely close before removing the blocking means. Illustrative of this typical arrangement is U.S. Pat. No. 3,895,461 (1975) which describes a blocking lever biased by a member connected to a second lever which can be moved by the closing of the first door. Upon the closing of the first door, a trigger lever is pivoted which causes the biasing member to move from its extended position to its retracted position thereby allowing the blocking lever to close followed by the door. The disadvantage of this system is that it involves multiple moving parts. Another similar device is described in U.S. Pat. No. 4,949,505 (1990) which involves a blocking lever and trigger lever connected to a actuating link which is connected to a secondary link or rod which holds a biasing member against the blocking lever. This particular sequencing device has even more moving parts as well as uses a larger quantity of material to effectuate door sequencing. Actuating arms and levers or bellcranks and levers are other popular means for blocking one door while simultaneously capturing the vertical motion of the other door to remove the blocking means. The preferred embodiment of U.S. Pat. No. 4,262,448 (1981) utilizes an actuating lever arm pivotally mounted to a timing slide bracket, essentially a blocking lever, which is removed from blocking one door when the other door contacts the actuating arm. An even more complicated system of levers is disclosed in U.S. Pat. No. 5,061,022 (1991). This system involves two protruding levers interconnected by an actuating link. The actuating link is connected to one lever by a bellcrank and the second lever by a pin and notch arrangement. The action of the closing door on the lever connected to the bellcrank translates the motion of the door to the actuating link which disengages the pin from the notch in the second lever allowing the other door to close.
U.S. Pat. No. 3,895,849 (1975) discloses a different arrangement for two levers and a sliding bar or link. In this case the levers or actuating means are connected to the doors with at least one being pivotally secured to one of the doors. The actuating means contacts a sliding bar at the rear of the cabinet. The bar is positioned such that the pivotally secured actuating means is blocked from further movement until the actuating means contacts a bellcrank on the slide bar to remove it from contact from the pivotally secured actuating means. Finally, U.S. Pat. No. 3,822,506 (1974) utilizes a plunger connected to a spring link which biases a lever which holds one door open. The first door contacts the plunger which allows the spring link to move into its retracted position removing the bias from the holding lever allowing the second door to close.
The interconnected lever systems, pivotally secured actuating means and plunger and spring lever means have several disadvantages. These door sequencing mechanisms have a large number of moving parts, use a lot of material in their construction and are intricate and costly to manufacture and install into safety cabinets. Actuating links and pivotal members must be individually manufactured and then connected to each other followed by installation of all the parts in an organized arrangement. These design arrangements are costly and time consuming to build. The unique and simplified design of the present invention overcomes the problems plaguing the sequencing mechanisms in the safety cabinet art.